#字符串。请用户输入用户名，打印欢迎语句，并打印九九乘法表。运行结果如图2.1所示。（要求使用三种格式化方式分别打印欢迎语句）
user_number = input("请输入你的用户名: ")  
user_number = user_number.strip()  
  
print(f"Hi {user_number.title()}, welcome!")  
  
print("Hi {}, welcome!".format(user_number.title()))  
    
print("Hi %s, welcome!" % user_number.title())  
   
for i in range(1, 10):  
    for j in range(1, i+1):  
        print(f"{j} x {i} = {i*j}", end="\t" if j < i else "\n")  # 使用 f-string 和 end 参数  
  
